The recent development of compound semiconductors has been remarkable, and the research and development for monolithic devices and apparatuses including not only microwave.millimeter wave laser devices, and transmitters and receivers for communication, but also antenna been intensively carried out. A elements have been intensively carried out. A conventional monolithic module is described on page 119 of "Microwave Journal, July 1986".
One type of a microwave antenna module comprises a semi-insulation GaAs substrate provided on a ground metal plate, and an active circuit including a low noise amplifier, a mixer, a switch, a transmitting amplifier, a phase shifter, an analog to digital (A/D) converter, etc., and a microstrip dipole antenna, respectively, provided on the semi-insulation GaAs substrate.
In this microwave antenna module, circuits of high integration (1 k gates to 10 k gates) such as the A/D converter, etc., and circuits of low integration (several transistors) are fabricated in the common semi-insulation GaAs substrate.
According to the conventional microwave antenna module, however, there is a disadvantage in that fabrication cost is largely increased, because faults tend to occur in the high integration circuits, much more commonly than in the low integration circuits. As a result, a module it is often determined to be faulty as a whole, despite having fully operational low integration circuits, thereby lowering fabrication yield.
On the other hand, a circuit of a high integration scale can be fabricated with high yield by using a silicon semiconductor. However, a microwave.millimeter wave passive circuit including a microstripline, an antennae element, etc. can not be integrated, because no semi-insulation substrate is available thereon.